Separater apparatus for handling compressed air

ABSTRACT

A compressed air filter comprising a tube in which there is an inner wall dfining an upper chamber which has its upper end closed by means of a plate that contains an inlet which opens into the chamber and there being a centrally located outlet which opens from said chamber. The inlet is adjacent to the inner wall and has a deflector means by which a mixture of air, solid particles oil and water droplets are moved downwardly in and to the upper chamber by swirling. There is an egg-shaped cylindrical tube attached to the plate which is approximately concentric within the inner wall and has a length greater than the wall defining a downward opening three-dimensional cylindrical annulus which varies across section containing the inlet opening so that incoming swirling mixture is accelerated in passing the narrowest point. A filter element is supported inside the egg-shaped cylinder which covers the outlet opening to filter solid particles in the mixture and a cylindrical tube which has its lower end closed by a plate. There is also a porous substance providing a filter means above a sump.

[ Nov. 13, 1973 SEPARATER APPARATUS FOR HANDLING COMPRESSED AIR [76]Inventor: Harry L. Wheeler, Jr., 1538 H untingdon Trail, Dunwoody, Ga, 7

22 Filed: Mar. 29, 1971 211 App]. No.: 129,264

Related U.S. Application Data [62] Division of Ser. No. 846,339, July31, 1969, Pat. No.

Primary Examiner-Bernard Nozick Attorney-Patrick F. Henry [57] ABSTRACTA compressed air filter comprising a tube in which there is an innerwall dfining an upper chamber which has its upper end closed by means ofa plate that contains an inlet which opens into the chamber and therebeing a centrally located outlet which opens from said chamber. Theinlet is adjacent to the inner wall and has a deflector means by which amixture of air, solid particles oil and water droplets are moveddownwardly in and to the upper chamber by swirling. There is anegg-shaped cylindrical tube attached to the plate which is approximatelyconcentric within the inner wall and has a length greater than the walldefining a downward opening three-dimensional cylindrical annulus whichvaries across section containing the inlet opening so that incomingswirling mixture is accelerated in passing the narrowest point. A filterelement is supported inside the egg-shaped cylinder which covers theoutlet opening to filter solid particles in the mixture and acylindrical tube which has its lower end closed by a plate. There isalso a porous substance providing a filter means above a sump.

7 Claims, 4 Drawing Figures SEPARATER APPARATUS FOR HANDLING COMPRESSEDAIR This application is a division of Ser. No. 846,339 filed July 31,1969 now US. Pat. No. 3,653,465 issued on Apr. 4, 1972.

BACKGROUND OF THE INVENTION 1. Field of the Invention The handling of agas and a separator which is classified in Class 55, Subclass 1.

2. Description of the Prior Art The prior art is discussed in thespecification of the above noted related patent and also in theprosecution thereof.

SUMMARY OF THE INVENTION An object of this invention is to provide acompressed air filter to separate and distribute the separated liquidfrom a mixture passing from an inlet to an outlet in the compressed airfilter device by means of swirling an egg-shaped tube.

Other and further objects and advantages of this invention will becomeapparent upon reading the following specification, the abstract of thedisclosure, and the claims with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF A PREFERRED EMBODIMENTWith reference to FIGS. 1-4, inclusive, the device in general isdesignated by reference numeral 80 and comprises a cylinder 81 having achamber 82 therein and having its upper end closed by a plate 83, whichis concentric with a slightly egg-shaped and longer inner cylinder 84,the upper end of which is also closed by plate 83. A top view of thearrangement is shown'in FIG. 1. The shape and location of the internaleggshaped cylinder 84 is such that an annular passage between the twocylinders 83' and 84 narrows at a point 86 to form a venturi. Thecylinder 81 is mounted on one end of and concentric with a larger andsecond collection cylinder 90 having a cross-sectional area of roughlytwice that of the chamber 82 in cylinder 81. An external, side-elevationview of this arrangement with the internal components indicated bydotted lines is shown in FIG. 2. Roughly one diameter of cylinder 84before the end thereof, a porous diaphragm 94 normal to the axis ofcylinder 90 is interposed across the collection cylinder 90 to form asump space. A drain 96 is provided to permit removal of collected waterfrom the sump cylinder 90. One hundred eight degrees opposite theventuri at 86 is a spiral vane 100 disposed between the walls of thecylinders 81 and 84 and starting even with the top of the two cylindersand spiraling downward at an angle between and 18 ending at the locationof venturi 86. The second spiral vane 102 starts again at the top ofcylinders 81 and 84 and spirals downward at the same angle endingimmediately under the initial point of the spiral vane 100. An inlet 106is provided in the plate 83 above and down stream of the start of vane100 and an outlet 108 is provided from the inside of the cylinder 84.

The operation of this arrangement is as follows, which also describesthe method employed:

Air enters the system through the inlet 106 and is conducted downward tobe deflected by the vane 100 into a spiral path parallel to vane 100.Vane 102 which is basically parallel to but 180 rotated from the vane100, provides the proper pressure distribution to force the air tocontinue its downward spiral path, even after it leaves the end of thevane 100. Entrained water is flung by centrifugal force against thewalls of cylinder 81 where it spirals down at an ever-increasing angleunder the action of the pressure forces created by vanes 100 and 102until it reaches the end of cylinder 81 which is inside and slightlybelow the top of collection cylinder 90. On reaching the enlargementboth air and water move rapidly outward and the air velocity drops by afactor of four. The water strikes and adheres to the walls of cylinderfrom whence it drips down past porous diaphragm 94, into the collectionsump 112'. The slowly moving air, free of entrained water turns andmoves upward through the interior of cylinder 84 to the outlet 108. Themechanical filter may be interposed between the inlet 106 and the inletto the outlet 108 for removal of solid matter but it is not necessary.

The intended operation of the device is move the air with as littleturbulence and at as low velocity as is consistent with the goals to beattained that being high water removal efficiency. Thus, the transitionbetween the inlet 106 and the vane must be as smooth as possible. Theangle of the vane 100 has been found to be important. Angles less that15 degrees tend to promote rotation of the water about the walls ofcylinder 81 without imparting sufficient downward component to force itinto the sump section rapidly enough to avoid redispersion. Anglesgreater than 18 degrees give the air too great an axial velocity withthe result that the centrifugal force acting on water particles movingthrough the viscous air does not have sufficient time to move the waterdroplets to the wall from whence they can drain into the sump, hencethey remain suspended.

The egg-shaped configuration of cylinder 84 contributes to theefficiency of the device, because air entering the system at inlet port106 is gradually accelerated in velocity by the narrowing passagewayuntil it reaches a peak at the venturi point 86. Here the centrifugalforce is at its greatest and the total path to be traversed by theinnermost water particle is at its least. The air is then graduallydiffused to a lower velocity as it rotates under the vane 102. A furtherdrop in velocity and therefore, turbulence may be given by reducing thediameter of cylinder 84 below the terminal points of vanes 100 and 102as shown in FIG. 2.

It is well known that air flow in a venturi duct section ispredominantly laminar. The cross-sectional area of the spiral ductformed by top vane 100 and cylinders 81 and 84 must be so adjusted thatthe air velocity is not sufficient to produce the turbulence or shatterthe droplets (due to shearing forces) yet does not reach a high level toassure a maximum of centrifugal force. Thus, in the most efficientembodiment of this invention means must be provided to vary the radialdimension of the passage as a function of an air flow. It has been foundthat optimum settings to cover a range of flows is practical.

The device handles the water laden air smoothly and with a minimum ofturbulence. Air entering inlet port 106 is smoothly accelerated andsmoothly decelerated reaching a peak velocity for only a short distanceat point 86. This velocity may be readily controlled. The air is kept asone large mass therefore, surface area exposure is minimized andredispersion is kept to a minimum. Some slight adiabatic expansionoccurs at point 86 thus cooling the air and throwing out even moremoisture; however, this effect is very slight and definitely secondaryto other effects.

Vanes 100 and 102 end abruptly after one-half revolution, in order,again to minimize surface exposure, to permit rapid deceleration anddiffusion of the air. Furthermore, it has been found that under theaction of gravity and the pressure distribution present in thecentrifugal chamber collected water leaving the end of vane 100 spiralsdownward at an ever increasing angle and dependent on operatingconditions in the chamber. Hence, prolonging the vanes prolongsopportunity for the redispersion because the air and water travel anunnatural path.

The sudden enlargement of the centrifugal chamber accomplishes severaldesired effects. First, the enlargement reduces the velocity of the airstream to a very low level, thus reducing turbulence and any opportunityfor redispersion. Secondly, the water is flung out against the walls ofcollection cylinder 90 and cmpletely away from the air stream which atthis point will be beginning an inward movement in order to return upthe inside of cylinder 81. The inlet diameter of cylinder 81 is selectedto reduce the velocity of the exiting air to a level such that theviscous drag of the air will be sufficient to carry only the verysmallest droplets as predicted by Stokes Law. However, any enlargementhere is made at the expense of increased velocity in the downward movingair. Hence the diameter of cylinder 81 must be a compromise stipulatedby operating conditions.

The action of the diaphragm is described in the above noted relatedapplication.

Desirably the velocity of the air should be limited to velocities belowwhich redispersion of shattering or entrained droplets be reduced to aminimum. lf low velocities are to be maintained, the relative diametersof cylinders 81 and 84 must be kept small in order to maximizecentrifugal force. For flow rates of 100 to 400 scfm this device hasbeen found most efficient if the inside diameter of cylinder 81 isapproximately 4 inches the outside diameter of cylinder 84 isapproximately 3 inches and the throat of venturi at 86 is adjusteddepending on average air flow requirements. To force air flows largerthan 300 and 400 scfm through these dimensions will produce velocitieswhich will cause redispersion of the water. To simply enlarge cylinders81 and 84 will increase the radii involved and hence reduce centrifugalforce and separation efficiency. It becomes necessary, then, in theexercise of this invention where higher air flow rates are to be handledto manifold several centrifugal separation chambers into largercollection cylinder 90, which is a chamber, or to manifold two or morecomplete assemblies described above, whichever, may be done mosteconomically.

While I have shown and described particular embodiments of my inventionsand named specific parts and typical applications and examples, this isby way of illustration only and does not limit the invention to particular uses or in any way.

What is claimed is:

l. A compressed air filter comprising an upper chamber having a closedupper end and an inner wall, a plate closing said upper end andcontaining an inlet opening into said chamber and a centrally locatedoutlet opening from said chamber, said inlet opening being adjacent tosaid inner wall, a deflector means in said inlet by which a mixture ofair, solid particles oil and water droplets are moved downwardly intosaid upper chamber by swirling, an egg shaped tube attached to saidplate within said inner wall and of length greater than the said wall todefine therewith a downward opening three-dimensional annulus of varyingcross-section containing the inlet opening so that the incoming swirlingmixture is accelerated in passing a narrowest point thereof, a secondtube having its lower end closed, a plate closing said second tube endand containing a valved opening, the inner walls of said tube and platedefining a lower chamber, attached to and larger in cross-section thansaid upper chamber, a porous filter means supported across said lowerchamber above a sump defined on one side by the filter means and theinner walls of said second tube and plate, said filter means being belowthe said egg shaped tube to distribute separated liquid from saidmixture passing from said inlet to said outlet.

2. The device in claim 1 said deflector means causing the air to spiraldownward at an initial angle no less than 15 and no more than 18.

3. The device in claim 1 the cross-sectional area of the lower chamberbeing twice the cross-sectional area of the upper chamber.

4. The device in claim 1 the narrowest dimension of the cylindricalannulus being variable to compensate for changes in airflow rate.

5. The device in claim 1 the lower end of the egg shaped tube beingdeformed to a circular cross-section above the point at which it entersto lower chamber.

6. The device in claim 1 said deflector means being a downwardly spiralvane disposed across said cylinderical annulus starting at the top ofsaid annulus underneath said inlet opening opposite the narrowest pointof said annulus and ending at said narrowest point.

7. The device in claim 6 a second downwardly spiraling vane disposedacross said annulus starting at the top of said annulus 180 opposite theinlet opening and ending at a point immediately below the start of thefirst vane.

* i i I!

1. A compressed air filter comprising an upper chamber having a closedupper end and an inner wall, a plate closing said upper end andcontaining an inlet opening into said chamber and a centrally locatedoutlet opening from said chamber, said inlet opening being adjacent tosaid inner wall, a deflector means in said inlet by which a mixture ofair, solid particles oil and water droplets are moved downwardly intosaid upper chamber by swirling, an egg shaped tube attached to saidplate within said inner wall and of length greater than the said wall todefine therewith a downward opening three-dimensional annulus of varyingcross-section containing the inlet opening so that the incoming swirlingmixture is accelerated in passing a narrowest point thereof, a secondtube having its lower end closed, a plate closing said second tube endand containing a valved opening, the inner walls of said tube and platedefining a lower chamber, attached to and larger in cross-section thansaid upper chamber, a porous filter means supported across said lowerchamber above a sump defined on one side by the filter means and theinner walls of said second tube and plate, said filter means being belowthe said egg shaped tube to distribute separated liquid from saidmixture passing from said inlet to said outlet.
 2. The device in claim 1said deflector means causing the air to spiral downward at an initialangle no less than 15* and no more than 18*.
 3. The device in claim 1the cross-sectional area of the lower chamber being twice thecross-sectional area of the upper chamber.
 4. The device in claim 1 thenarrowest dimension of the cylindrical annulus being variable tocompensate for changes in airflow rate.
 5. The device in claim 1 thelower end of the egg shaped tube being deformed to a circularcross-section above the point at which it enters to lower chamber. 6.The device in claim 1 said deflector means being a downwardly spiralvane disposed across said cylinderical annulus starting at the top ofsaid annulus underneath said inlet opening 180* opposite the narrowestpoint of said annulus and ending at said narrowest point.
 7. The devicein claim 6 a second downwardly spiraling vane disposed across saidannulus starting at the top of said annulus 180* opposite the inletopening and ending at a point immediately below the start of the firstvane.